Digital wireless communication system for simultaneously conveying full rate speech data and dedicated user data

ABSTRACT

In a digital wireless communication system wireless communication stations or radio base stations constitute frames to be conveyed over an air-interface for simultaneously comprising full rate speech data and dedicated user data. A speech coder in the digital wireless communication system generates the speech data while operating at a full rate. A user data application in the digital wireless communication system generates the dedicated user data. The system can set different service configurations supporting simultaneous transmission of speech data and dedicated user data, and can also include signaling data in the frames.

FIELD OF THE INVENTION

The present invention relates to a digital wireless communicationsystem. Such a system can be a cellular or other wireless communicationsystem including wireless communication stations such as mobile radiohandsets, combined mobile radio data processing devices, cordlesstelephones, or any other suitable wireless telephone device. The systemcan be any frame oriented system suitable for conveying speech data,control data, and user data.

BACKGROUND OF THE INVENTION

From the handbook “Speech and Audio Coding for Wireless and NetworkApplications”, B. S. Atal et al., Kluwer Academic Publishers, 1993, pp.85-92, a variable speech or adaptive rate coder is known for use in adigital cellular telephone system. From speech signal samples, thespeech coder generates speech coder data which are typically containedin 20 ms frames. Periods of silence in the speech signal and backgroundnoise are coded at a lower rate so that system capacity is increased.For signaling data to be sent, the system can instruct the speech coderto encode the speech at half rate for one or two frames, allowing theremaining bits which would have been used for full rate speech datainstead. Because speech is only coded at half rate for 20-40 ms, speechquality is not significantly degraded, though the amount of signalingdata that can be conveyed without causing degrading of speech quality islimited.

The proposed TIA/EIA/IS-707 Standard defines data service options forwideband spread-spectrum systems. At a Rate Set 1, at full rateoperation of a speech coder in the system, so-called Primary Traffic isconveyed in bits/frame. At a lower rate of the speech coder, the framemay contain signaling traffic bits or so-called Secondary Traffic bits.The signaling bits are to be considered as in-band data and theSecondary Traffic can consist of user data. Particularly when there is adesire to simultaneously convey speech data and a moderate amount ofuser data, the speech quality is substantially degraded. This is due tothe fact that the speech coder is then forced to operate at a lower ratefor a great number of speech frames, i.e., not only for framescontaining silent speech periods and/or background noise information butalso for speech frames carrying meaningful speech data. Typicalapplications today in which considerable amounts of data have to beconveyed, either uni-directional or bi-directional, are Internetapplications, or the like. In this respect, there is a trend to coupleor integrate cellular phones with data devices or personal computers.

Thus, what is needed is a mechanism of simultaneously conveying speechdata and substantial amounts of user data without substantiallydegrading speech quality.

SUMMARY OF THE INVENTION

It is an object of the invention to provide a digital wirelesscommunication system simultaneously conveying high quality speech signaldata and optimal rate dedicated user data.

It is another object of the invention to further optimise the throughputof the dedicated user data in the event speech signal data can betransmitted without substantial decrease of speech quality.

It is yet another object of the invention to also simultaneouslyexchange signaling data.

It is yet another object of the invention to flexibly adjust the type ofdata to be exchanged between the wireless communication infrastructurenetwork and the wireless communication stations.

It is yet another object of the invention that the system canindependently act upon speech data and dedicated user data, preferablyusing different protocols for speech data and dedicated user data,preferably applying a protocol most suitable for processing dedicateduser data.

It is yet another object of the invention to make available a means forexchanging data which is optimal when data traffic is extended over along period but is irregular.

In accordance with the invention, a digital wireless communicationsystem is provided which comprisies a wireless communicationinfrastructure network and a plurality of wireless communicationstations configured for wireless communication with the wirelesscommunication infrastructure network, the communication using anair-interface protocol for exchanging data in frames, which frames areconstituted for simultaneously comprising speech data generated at afull rate by a speech coder and dedicated user data generated by a userdata application

A great advantage is that it always can be guaranteed that the speechcoder can operate at full rate on meaningful speech signal samples sothat speech quality is not degraded, while at the same time dedicateduser data can continuously and uninterruptedly be conveyed. On aframe-by-frame basis, the rate of the speech coder can be adapted sothat maximum throughput can be achieved in conveying the dedicated userdata. Preferably having a dedicated user data channel independent of thespeech data channel on the same air-interface frame provides low costsimultaneous voice and data services.

Preferably, data throughput of dedicated user data is increased atinstances where speech data can be transmitted at a lower rate withoutloss of speech quality. Preferably, speech and dedicated user data areindependently routed and processed by the system. Further embodimentsare discussed hereinafter.

The invention can advantageously be used for Internet applications, orthe like. Another very advantageous application is conveying dedicateduser data while using a bi-directional data link that is open for a longperiod of time. Herewith, applications such as interactive paging andweb-chatting, or even simultaneous exchange of still picture data withhigh quality cellular voice data link, can be easily implemented becausethe data link is open all the time and can be used at choice, i.e. fordata transmission of dedicated user data system resources are only usedwhen needed. Another great advantage is that the user data link does notinterfere with usual signaling or control in the cellular system, i.e.cellular system control is not made more complex as compared to existingsystems.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 schematically shows a digital wireless communication system inaccordance with the invention.

FIG. 2 is a block diagram illustrating an embodiment of a wirelesscommunication station in accordance with the invention.

FIG. 3 is a block diagram illustrating an embodiment of a radio basestation for use in a wireless communication infrastructure network inaccordance with the invention.

FIG. 4 is a frame illustrating an embodiment of simultaneoustransmission of full rate speech coder data and dedicated user data inthe digital wireless communication system of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 schematically shows a digital wireless communication system 1 inaccordance with the invention. The system 1 comprises a wirelesscommunication infrastructure network 2 of radio base stations 3 and 4covering radio zones 5 and 6, respectively, and of a switching center 7.The system 1 further comprises wireless communication stations 8 and 9for wireless communication with the wireless communicationinfrastructure network 2. In principle, the wireless communicationsystem 1 can be any digital wireless system such a CDMA or TDMA system.In the embodiment given, the system 1 is a CDMA system. At a logicalsystem level, the data to be transmitted and received are multiplexed inframes which will be described in the sequel. The frames are transmittedvia a so-called air-interface. To this end, all data, such as speechdata, dedicated user data and control data are modulated on a carrierfrequency. Such techniques are well-known in the art and are notdescribed in detail here. The switching center 7 is coupled to aswitched telephone network 10 of fixed network subscribers so that thewireless communication stations 8 and 9 can call such fixed networksubscribers. The switching center 7 transparently exchanges speech databetween the wireless communication infrastructure network 2 and theswitched telephone network 10, i.e., the speech data are not subjectedto a further processing protocol. The switching center 7 is furthercoupled to a so-called IWF, an Inter Working Function through which awireless communication station can request a packet data service.Herewith, data transmission is instantiated for simultaneous operationwith speech or voice communication. The Inter Working Function IWFcomprises a protocol stack 11 and a router 12 which is coupled to anInternet Service Provider 13 coupled to an Internet 14. The dedicateduser data are thus exchanged using a non-transparent link protocol,i.e., dedicated user data are subject to processing between end-users.Such processing and routing of dedicated user data as such is well-knownin the art and will not be described in further detail here. In theexample given, packet data service is based on a simple InternetProtocol EP using Internet standard protocol stacks. Packet data servicemay also be based on other protocols such as using CDPD emulation,Cellular Digital Packet Data, as defined in Service option 16 of saidTIA/EIA/IS707 Standard.

FIG. 2 is a block diagram illustrating an embodiment of the wirelesscommunication station 8 in accordance with the invention. The wirelesscommunication station 8 comprises a speech coder 20 coupled to amicrophone 21 and an earpiece or speaker 22. Sampling and reconstructionfunctionality, using an analog-to-digital converter and adigital-to-analog converter, is included in the speech coder 20. Thewireless communication station 8 further comprises a user dataapplication 23 for bi-directional providing dedicated user data 24, andprocessing means 25 for multiplexing and demultiplexing speech anddedicated user data. The user data application may be integrated in thewireless communication station 8, as shown, or may be performed by aseparate device such as a personal computer coupled to the wirelesscommunication station 8. The processing means 25 controls the speechcoder 20 and the user data application 23. Particularly, the processingmeans 25 is configured to set the rate of the speech coder 20. Thewireless communication station 8 further comprises a receive andtransmit branch, coupled to the processing means 25, for receiving andtransmitting radio frequency signals. The receive branch comprises aradio frequency reception circuit 26, a mixer 27, and a demodulator 28,and further a PseudoNoise-generator, 29 coupled to the mixer 27. Thetransmit branch comprises a modulator 30, a mixer 31, and a radiofrequency transmit circuit 32, and further a PseudoNoise-generator 33.The RF-circuits 26 and 32 are coupled to an antenna 34 through aduplexer 35.

FIG. 3 is a block diagram illustrating an embodiment of the radio basestation 3 for use in the wireless communication infrastructure network 2in accordance with the invention. The radio base station 3 comprisesseveral radio frequency transceivers of which one is shown in FIG. 3.Shown is an antenna 40 coupled to a duplexer 41 coupled to processingmeans 42 through radio frequency and modulation and demodulationtransmit and receive branches similar to the transmit and receivebranches shown in FIG. 2, and not shown in detail here. The radio basestation 3 further comprises a speech coder 43 bi-directionally coupledto the switching center 7 shown in FIG. 1. Alternatively, the speechcoders can be located in the switching center 7. The radio base station3 further comprises a radio link protocol 44 for independent handling ofdedicated user data simultaneously comprised in frames of speech data.Similar to what is described in the TIA/EIA/IS-707 Standard, a so-calledLink Layer connection is opened for the wireless communication station 8for rendering the wireless communication station's packet data serviceactive. The packet service must be instantiated initially. This can bedone at powering up of the wireless communication station, or at userinstantiation after powering up. The Link Layer connection can be eitheractive or dormant. While the Link Layer connection is dormant, thewireless communication station 8 may use other services. The switchingcenter 7 will not page the wireless communication station 8 fordedicated user data packets intended for the station 8 during such otherservices, e.g., a circuit switched data service such as fax, with theexception of a valid simultaneous voice call. Dedicated user datapackets that arrive at the IWF will be discarded if the other service isnot valid for concurrent operation. Dedicated user data packets may belost, however, the lost packets in general will be detected andretransmitted by higher layer protocols when the other service is ended.

FIG. 4 is a frame 50 illustrating an embodiment of simultaneoustransmission of full rate speech coder data and dedicated user data inthe digital wireless communication system of FIG. 1. The frame 50 has aframe length FL of 20 msec, a length typically used when transmittingspeech parameters generated by a speech coder through the air interface.According to the invention, in addition to speech data SD, generated bythe speech coder 20 or 43 at full rate, the frame comprise dedicateduser data DUD. Herewith, transmission of speech data is guaranteed whilemaintaining the best speech quality with the coder used, and continuoustransmission of dedicated user data. A multi-mode bit MM, together withthree other control bits CB in the speech data part SD control the rateof the coder at reception side, and the number of bits used for dataover voice, i.e., the number of bits of the dedicated user data DUD. Ifthe speech coder 20 detects silent periods in the speech signal to beencoded, or when background noise information is to be conveyed, theprocessing means 25 adapt the rate of the speech coder 20 to a lowerrate so that more bits are available in the corresponding frame forconveying the dedicated user data DUD. In addition to the shown bits,the frame 50 further comprises header and error control/tailer bits 51,52, and 53. The frame typically contains a total of 288 bits so that theframe rate is 14,400 bits. At full rate, the speech data SD, includingcontrol, comprise 172 bits, and the dedicated user data, includingcontrol, 95 bits. With the multi-mode bit MM set to ‘0’, the coder 20operates at full rate. With the multi-mode bit MM set to ‘1’, the coder20 operates at a lower rate, the particular rate further beingdetermined by the control bits CB. Then, with the control bits CB set to‘100’ or ‘101’, the speech coder 20 operates at ½ rate or ⅛ rate,respectively. The excess bits are added to the dedicated user data DUD.With the control bits CB set to ‘111’, when the multi-mode bit MM is setto ‘1’, all bits in the frame 50 are available for exchanging thededicated user data DUD. The frame 50 represents the frame at theair-interface when the system is in a traffic channel state. In additionto the described combination of speech data and dedicated user data, theframe may contain other combinations of data, particularly signalingdata. The table below shows possible combinations of data in the frame50, i.e., a service configuration as regards the types of traffic in thetraffic channel, indicated with Frame No., SD being the speech data,PRIM being primary data, SEC being secondary data, DOV being data overvoice, and TOT being the total number of bits. Under the headingMultiplexed Voice/Data Services, a symbol ‘x’ indicates the selection ofmultiplexed services. Multiplexed Voice/Data Services Frame CoderInformation Bits per Frame No. SD SIG SEC DOV Rate PRIM SIG SEC DOV TOT1 x 1  1+171 − − − 172 2 x ½ 80 — — — 80 3 x ⅛ 16 — — — 16 4 x — — — —88+7 95 5 x x 1  1+171 — — 88+7 267 6 x x ½ 80 — — 88+7 175 7 x x ⅛ 16 —— 88+7 111 8 x x x ½ 4+80 — 88 88+7 267 9 x x x ⅛ 4+16 — 152 88+7 267 10x x — — — 4+168 88+7 267 11 x x x ½ 4+80 88 — 88+7 267 12 x x x ⅛ 4+16152 — 88+7 267 13 x x — — 4+168 — 88+7 267 14 x x ½ 4+80 88 — — 172 15 xx ⅛ 4+16 152 — — 172 16 x — — 4+168 — — 172 17 x x — — — 88 — 172 18 x x— — — 152 — 172 19 x — — — 4+168 — 172

Frame No. 5 or category may be used for full rate circuit switched data,primary and DOV.

Dedicated user data are exchanged using a packet data service, if theLink Layer connection is open and active, as described before. The LinkLayer connection is active if cellular system resources such as atraffic channel are assigned. If, after a predetermined period of timethere is no data to send, the cellular resources, i.e., the connectionvia the traffic channel, will be released to conserve cellular systemresources but the Link Layer will remain open and go to the dormantconnection state. As long as the Link Layer remains open, a connectionmay be reactivated whenever dedicated user data arrives or needs to besent. A voice call may be originated at any time simultaneous with aninstantiated packet data service via a concurrent service negotiationprocess to configure the coder within the altered service option inaccordance with the above table. The wireless communication station 8can request a default service configuration associated with a serviceoption at call origination, and can request new service configurationsduring traffic channel operation. If the wireless communication station8 requests a service option that is acceptable to the radio base station3, they both begin using the new service configuration. If the wirelesscommunication station 8 requests a service option that is not acceptableto the radio base station 3, the radio base station 3 can reject therequested service configuration or propose an alternative serviceconfiguration. If the radio base station 3 proposes an alternativeservice configuration, the wireless communication station can accept orreject the base radio base station's proposed service configuration, orpropose yet another service configuration. This process, so-calledservice negotiation, ends when the wireless communication station 8 andthe radio base station 3 find a mutually acceptable serviceconfiguration, or when the wireless communication station 8 or the radiobase station 3 rejects a service configuration proposed by the other. Itis also possible for the radio base station 3 to request a defaultservice configuration associated with a service option when paging thewireless communication station 8 and request new service configurationsduring traffic channel operation. The service negotiation proceeds asdescribed above, but with the roles of the wireless communicationstation 8 and the radio base station 3 reversed.

In view of the foregoing it will be evident to a person skilled in theart that various modifications may be made within the spirit and thescope of the invention as hereinafter defined by the appended claims andthat the invention is thus not limited to the examples provided.

1. A wireless communication station for use in a digital wirelesscommunication system which comprises a wireless communicationinfrastructure network, the system being configured for wirelesscommunication between the wireless communication station and thewireless communication infrastructure network, which communication usesan air-interface protocol for exchanging data in frames, the framesbeing constituted for simultaneously comprising speech data generated ata full rate by a speech coder comprised in the wireless communicationstation, and dedicated user data generated by a user data application inor coupled to the wireless communication station.
 2. A wirelesscommunication infrastructure network comprised in a digital wirelesscommunication system which comprises a plurality of wirelesscommunication stations, and which is configured for wirelesscommunication between the wireless infrastructure network and thewireless communication stations, which communication uses anair-interface protocol for exchanging data in frames, the frames beingconstituted for simultaneously comprising speech data generated at afull rate by a speech coder comprised in the wireless communicationinfrastructure network, and dedicated user data generated by a user dataapplication in or coupled to the wireless communication infrastructurenetwork.
 3. A method for exchanging data in frames between a wirelesscommunication infrastructure network and a plurality of wirelesscommunication stations comprised in a digital wireless communicationsystem, the method comprising constituting of the frames such that theframes simultaneously comprise speech data generated at a full rate of aspeech coder comprised in the system, and dedicated user data generatedby a user application comprised in the system.
 4. A traffic frame forconveying data in a digital wireless communication system comprising awireless communication infrastructure network and a plurality ofwireless communication stations, which system is configured for wirelesscommunication between the wireless communication infrastructure networkand the wireless communication stations, which communication uses anair-interface protocol for exchanging data in frames, the frames beingconstituted for simultaneously comprising speech data generated at afull rate by a speech coder comprised in the system, and dedicated userdata generated by a user data application comprised in the system.